Improving Mood Also Helps Glycemic Control : HbA_1c levels were 'significantly lower than baseline'during the depression-free interval of maintenance.

Glycemic control, body mass index, and diabetes self-care improved significantly in type 2 diabetics with major depressive disorder who used bupropion for both acute and maintenance therapy, a two-phase open-label study found.

“Our study affirms the importance of depression management in diabetic patients in its potential to improve glycemic control, even though the mechanisms involved are not fully understood,” wrote study authors Patrick J. Lustman, Ph.D., of the Washington University School, St. Louis, and colleagues. “This advantage could lead to better outcomes, measured not only in quality of life but also in reduced or delayed onset of complications.”

The researchers evaluated data from a two-phase (acute and maintenance) open-label depression treatment trial in type 2 diabetics with major depressive disorder to determine whether treatment with bupropion hydrochloride extended release (Wellbutrin XL) affected glycemic control.

They assessed whether hemoglobin A_1c (HbA_1c), described as an “aggregate measure of glycemic control over the 120-day period before testing,” improved with treatment and whether mood, diabetes self-care, and anthropometric changes also affected a change in HbA_1c.

Of the 93 patients enrolled, 75 completed the acute 10-week bupropion treatment (mean dosage 334 mg/day). Of the 18 patients who discontinued treatment during the acute phase, 6 withdrew because of side effects, with increased anxiety being the most common. Those patients who withdrew were more likely to be black and older at depression onset; however, there were no significant between-group demographic differences among those completing the acute phase.

Of the 75 patients who completed the acute phase, 63 (84%) had remittance from their depression and therefore were eligible to continue with maintenance therapy. Of that group, 8 patients (13%) discontinued treatment prematurely. The remaining 55 patients (87%) went on to complete the full 24-week maintenance phase; no one in that group suffered a recurrence.

Compared with their baseline values, patients who had relief from depression also significantly improved their adherence to diet and exercise regimens during the 10-week acute phase and 24-week maintenance phase. Glucose testing adherence was not significantly affected throughout the study (Diabetes Care 2007;30:459–66).

“Depression remitted in 68% of those who started bupropion treatment and in 84% of those who completed the acute phase,” the authors wrote.

For the 55 patients who completed the maintenance phase, “changes from baseline over the maintenance interval were significant for weight and [body mass index]; total body fat mass showed a trend toward significance, and, in this instance, the reduction in percent body fat was also significant,” the authors found.

The overall HbA_1c decrease from baseline during the acute phase was a mean of −0.5, and this effect “was completely attributable to changes in the subset showing remission … as the change in those who did not show a remission was minimal and insignificant,” they continued. These levels “remained significantly lower than baseline (−0.7) during the depression-free interval of maintenance,” the researchers noted.

This two-phase study was funded by the National Institutes of Health and GlaxoSmithKline Inc., the manufacturer of Wellbutrin XL.